How much radiation do you get in a year?

How it is calculated

Radon at home. The national radon map of the Greek Atomic Energy Commission (EEAE) gives the average radon concentration in the homes of each regional unit; the highest is Xanthi, 145 Bq/m³5. For the country as a whole, the EEAE gives an average concentration of 77.3 Bq/m³6 in ground-floor homes, weighted by population, and that is the calculator’s default. We convert concentration into dose with the UNSCEAR method, which assumes 80% of the time is spent indoors1, an equilibrium factor of 0.41 between radon and its decay products, a dose coefficient of 9 nSv per Bq·h/m³1, and 0.18 nSv per Bq·h/m³1 for the radon that passes into the blood. With this method, 50 Bq/m³ gives about 1.3 mSv/year1.

The average for your area is not your home. According to the EEAE, radon levels vary from one space to another, depending on the geology underneath and the construction of the building7, and only a measurement shows how much a particular home has. More on radon and how it is measured in the Greek article «Ραδόνιο στο σπίτι» (in Greek).

The other natural sources. Cosmic radiation, the ground, food, thoron and radon in outdoor air are entered at the UNSCEAR worldwide averages, not at values for your own area.

Flights. The dose from a flight changes with the route, and for the same route mainly with the solar cycle and the flight altitude2. We found no official figure for flights from Athens, so we use three routes of the German radiation protection authority, Frankfurt–Rome, Frankfurt–Las Palmas (Canary Islands) and Frankfurt–New York, and from the range of each we take the highest value. Pick the route closest to yours.

Medical exams. For each exam we use the average typical effective dose across 36 European countries, from a European Commission survey with data from 2007–2010. For the panoramic dental X-ray, which is not in the survey’s table, we use the typical value of the United Kingdom. These are averages: the dose from a particular exam can be lower or higher.

Comparison. The worldwide average from natural sources is 3.0 mSv/year1. For Greece, the EEAE estimated 2.7 mSv/year8 from natural sources and 1.8 mSv/year8 per person from diagnostic medical exams, with its own measurements and data from medical radiology laboratories. Here the natural sources other than radon at home are worldwide averages, so the result does not compare one-to-one with the EEAE figure.

The limit of 1 mSv a year for the public9 applies to the sum of exposures from authorised practices, that is from activities involving radiation, and does not apply to medical exposures, which is why it is not placed beside the result as a yardstick. Nor does the result say whether you are at risk: it is an estimate of the dose, compared with averages.

The calculator’s values

Radon in Greece by regional unit

The average radon concentration in homes in each of the 74 regional units that have a value on the EEAE national radon map5, highest first. The EEAE shows an average only where the number of homes measured is statistically representative, and says the national map will be completed gradually. Names are as Eurostat writes them in Latin script, with the Greek name beside them.